#include<iostream>
#include<vector>
#include<unordered_map>

using namespace std;
class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        unordered_map<int, int> hash;
        for (auto& e : nums) {
            hash[e]++;
            if (hash[e] > 1) {
                return true;
            }
        }
        return false;
    }
};
int main(){

	return 0;
}